Photosensitive elements and process

ABSTRACT

PHOTOSENSITIVE ELEMENTS AND A PROCESS OF PHOTOGRAPHIC REPRODUCTION ARE DESCRIBED EMPLOYING A PHOTOSENSITIVE COMPOSITION COMPRISING A HETEROCYCLIC NITROGEN COMPOUND AND A KETOMETHYLENE COMPOUND OR A REACTIVE CYCLIC AMMONIUM QUATERNARY SALT WHICH ON EXPOSURE TO ACTINIC RADIATION REACT TO FORM A DYE.

United States Patent ffice Patented Aug. 3, 1971 U.S. Cl. 96-90 16Claims ABSTRACT OF THE DISCLOSURE Photosensitive elements and a processof photographic reproduction are described employing a photosensitivecomposition comprising a heterocyclic nitrogen compound and aketomethylene compound or a reactive cyclic ammonium quaternary saltwhich on exposure to actinic radiation react to form a dye.

This invention relates to photographic reproduction of images and toradiation sensitive compositions and elements useful for photographicreproduction. In a particular aspect it relates to radiation sensitivecompositions and elements for copying images by a dry process.

Many compounds and compositions are known which are useful for thereproduction of images by photographic means. Photographic systems areknown in which photoexposure produces either a visible or a latent imageby such means as the photo-reduction of a heavy metal salt, such assilver halide; the photoinduced reaction between a colorless pair ofcompounds to give a colored reaction product; the photobleaching of acolored compound to a colorless form; the photopolymerization of anunsaturated mnomer to a polymer; the photocrosslinking of a polymer to ahardened form; etc. Despite this wide variety of photographic materials,each of these systems has certain advantages and certain drawbacks whichmakes them useful for some types of photographic reproduction anddisadvantageous for other types of photographic reproduction. Thus,there is a continual search for new photosensitive compounds andcompositions which will combine in a single system a maximum of theadvantages associated with different prior art photographic systemswhile minimizing their disadvantages.

Accordingly, it is an object of this invention to provide novelphotographic compositions and elements.

It is another object of this invention to provide novel photographicelements in which an image is formed di rectly upon exposure to lightwithout need for further development.

It is yet another object of this invention to provide a novel dryphotographic system which obviates the need for liquid chemicaldevelopment.

It is still another object of this invention to provide a dry processfor producing photographic images using the novel photographiccompositions and elements of this invention.

The above and other objects of this invention will become apparent tothose skilled in the art from the further description of the inventionwhich follows.

In accordance with the present invention, we have found thatphotosensitive elements can be prepared from a photosensitivecomposition comprising as a first component a salt of a heterocyclicnitrogen compound and as a second component a ketomethylene dyeprecursor compound or a reactive cyclic ammonium quaternary salt. By theterm reactive cyclic ammonium quaternary salt We mean a cyclic ammoniumquaternary salt which contains in the heterocyclic ring an activemethylene group adjacent the nitrogen atom. Upon exposure to actinicradiation these two components react to form a colored dye in exposedareas.

The heterocyclic nitrogen compounds which are useful in the practice ofthis invention include pyrimidinium salts having the structural formulaand pyridinium salts having the structural formula fif/ wherein R and Rare independently a hydrogen atom, an alkyl group typically having 1 to12 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl,isobutyl, tertiary butyl, hexyl, octyl, decyl, etc.) includingsubstituted alkyl groups (e.g., benzyl, phenylpropyl, etc.) or an arylgroup typically having 1 to 2 rings (e.g., phenyl, tolyl, naphthyl,etc.); R is a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group or aryl group, as defined above for R and R oran amino group; and X is an anion such as an acetate ion, a sulfate ion,a p-toluenesulfonate iron, a tetrafluoroborate ion, a halogen ion, etc.

Typical heterocyclic nitrogen compounds which are useful in the practiceof this invention are pyridinium acetate,

pyridinium p-toluenesulfonate,

pyridinium chloride,

l-methylpyridinium acetate,

l-ethyl-pyridinium p-toluenesulfonate, l-phenyl-pyridinium acetate,l-benzyl-pyridinium tetrafluoroborate, pyrimidinium acetate,

pyrimidinium p-toluenesulfonate, l-methyl-pyrimidinium acetate,1,2-diethyl-pyrimidinium p-toluenesulfonate,Z-ethyl-l-phenyl-pyrimidinium tetrafluoroborate,2-chloro-l-ethyl-pyrimidinium acetate, Z-amino-l-methyl-pyrimidiniump-toluenesulfonate, etc.

The ketomethylene compounds which are useful in the photosensitivecompositions of the present invention include barbituric acids havingthe structural formula (III) R C wherein Z is an oxygen or a sulfuratom, and each R is independently a substituted or unsubstituted alkylgroup or an aryl group, as defined above; 2-pyraZolin-5-ones having thestructural formula wherein R is a hydrogen atom, a substituted orunsubsti tuted alkyl group or an aryl group, as defined above and R is asubstituted or unsubstituted alkyl group or an aryl group, as definedabove; and 3 cyano-2(5H)-furanones having the structural formula whereinR is a substituted or unsubstituted alkyl group or an aryl group, asdefined above. These furnanone compounds and the method of theirpreparation are more fully dsecribed in copending patent application ofJ. A. Ford and C. V. Wilson U.S. Ser. No. 555,239, filed June 6, 1966,now US. Pat. No. 3,468,912 issued Sept. 23, 1969.

Typical of the ketomethylene compounds which are useful in the practiceof this invention are 1,3-diethylbarbituric acid, 1,3-dibuty1barbituricacid, 1,3-diphenylbarbituric acid, 3-benzyl-l-phenylbarbituric acid,1,3-diethyl-Z-thiobarbituric acid, 1,3-diphenyl-2-thiobarbituric acid,1,3-dibenzyl-Z-thiobarbituric acid, 1,3-diethyl-2-pyrazolin-5-one,1,3-diphenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one,3-benzyl-l-ethyl-Z-pyrazolin-S-one, 3-cyano-4-methyl-2 H) -furanone,3-cyano-4-ethyl-2'(5H)-furanone, 3-cyano-4-phenyl-2 5 H) -furanone,4-benzyl-3-cyano-2 (5 H) -furanone, etc.

Typical reactive cyclic ammonium quaternary salts, which are useful inthe practice of this invention are the benzothiazolium salts having thestructural formula where R, and R are each an alkyl group typicallyhaving 1 to 8 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl,n-butyl, isobutyl, amyl, hexyl, octyl, etc.); and X is an anion asdefined above. Representative benzothiazolium salts include2,3-dimethylbenzothiazolium p-toluenesulfonate,2,3-diethylbenzothiazolium acetate, 3-ethyl-2-methylbenzothiazoliump-toluenesulfonate, 3-butyl-2-ethylbenzothiazolium tetrafluoroborate,etc.

Upon exposure to actinic radiation the compositions of this inventionundergo a change in photoexposed areas from a colorless or pale coloredform to an intensely colored dye. While we do not wish to be bound byany particular theory as to the reason or mechanism for the dyeformation, it is believed that upon exposure to actinic radiation theheterocyclic nitrogen compound cleaves giving a reactive intermedateWhich supplies the polymethine chain to join two of the ketomethylene orreactive cyclic ammonium quaternary salt moieties to form a dye.

Photographic elements employing the photosensitive compositions of thisinvention can be prepared by methods conventional in the art. Thephotosensitive composition can be imbibed into an absorbent support, oran absorbent material coated on a base support, it can be incorporatedin a binder which is then coated on a base support, or it can beincorporated in a self-supporting binder.

The photosensitive compositions of this invention preferably employ amolar excess of the ketomethylene or reactive cyclic ammonium quaternarysalt component. Preferably, for each part of the heterocyclic nitrogencomponent in the composition, there is employed from two to ten parts ofthe ketomethylene or reactive cyclic ammonium quarternary saltcomponent.

Suitable absorbent supports include fibrous materials such as paper,cloth, parchment, etc., ceramic materials, gelatin, synthetic polymerssuch as poly (vinyl alcohols), poly(vinyl phthalates), carboxymethylcellulose, cellulose ether phthalates, copolymers of alkyl acrylateswith acrylic acid, etc., and the like. The wearing and handlingproperties and the dimensional stability of elements prepared With theseabsorbent materials can be improved by coating certain of them, e.g.,gelatin and the polymeric materials, on such non-absorbent base supportsas metal sheets and foils, polyester film base, e.g., poly(ethyleneterephthalate) film, poly(ethylene sebacate) film, poly (ethyleneadipate) film, etc., cellulose ester film base, e.g., cellulose nitratefilm, cellulose acetate film, cellulose acetate-butyrate film, celluloseacetate-propionate film, etc., and the like.

The photosensitive composition is imbibed into the absorbent support bycontacting the support with a solution of the reactive components in asolvent therefor such as water, an alkanol, e.g., methanol, ethanol,isopropanol, etc., or the like. The solution can be swabbed or sprayedonto the surface of the absorbent support or the support can be immersedinto the solution. The two reactive components need not be imbibed intothe support at the same time. The support can be first contacted with asolution of one of the reactive components and then subsequently theother reactive component can be imbibed into the support.

Binders in which the photosensitive reactants of this invention can beincorporated to form a coating composition include such film-formingvehicles as gelatin, olefinic polymers, such as polyethylene,polystyrene, butadienestyrene copolymers, poly(ethylene oxides),poly-(vinyl chloride), poly(vinyl alcohol), poly(vinyl acetate), poly(vinyl chloride-acetate), poly(ethylene-vinyl acetate), poly(vinylacetals), copolymers of vinylidene chloride with such monomers as vinylacetate, acrylonitrile, and ethyl acrylate, and polyacrylate andmethacrylate esters such as poly(ethyl acrylate) and poly(butylmethacrylate); polyesters and copolyesters of glycols and dibasic acidssuch as terephthalic, isophthalic, sebacic and adipic acids; celluloseesters, such as cellulose acetate, and cellulose acetate-butyrate; andcellulose others such as methoxyethyl cellulose.

A coating composition for preparing photosensitive elements is preparedby dissolving or dispersing the photosensitive components in a binder.The photosensitive components can each comprise from about 5 to about 25percent by weight of the coating composition. As indicated above, amolar excess of the ketomethylene or reactive cyclic ammonium quaternarysalt component is preferably employed. The coating composition can alsoinclude other known addenda, utilized in known amounts for their knownpurposes, such as agents to modify the flexibility of the layer,tomodify its surface characteristics, to modify the adhesivity of thebinder to its support, and the like. The coating composition isgenerally coated from a suitable solvent by any Well-known method suchas extrusion coating, hopper coating, dip coating, doctor-blade coating,etc. Coating thicknesses of 0.0005 to 0.01 inch, and preferably 0.002 to0.004 inch, can be employed. The support on which the composition iscoated can be any of the wellknown supports used for photographicpurposes, for example, those absorbent and base supports mentionedabove.

The photosensitive elements of this invention can be exposed bytechniques well known to those skilled in the art. Since thephotosensitive compositions of this invention exhibit their greatestsensitivity to radiation in the ultraviolet region of the spectrum,light sources, such as carbon arcs and mercury vapor lamps, which arerich in such radiation are preferably employed.

Since the photosensitive elements of this invention provide a print-outimage directly on photoexposure, they find use in applications where areproduction is required employing a simple process which involves aminimum numher of operating steps and which avoids the use of liquidchemical developing agents. Document copy and related fields are typicalof the areas in which the elements of this invention can be employed.

Certain of the compositions of this invention are sensitive to heat aswell as ultraviolet radiation and elements prepared from them can beemployed in thermographic processes as well as photographic processes.Such processes are described in our copending US. application Ser. No.772,032, filed Oct. 30, 1968, now US. Defensive Publication Q772,032,published Oct. 28, 1969.

The following examples are included for a further understanding of thisinvention.

EXAMPLE 1 Under safelight conditions 2 grams of 1,3-diphenylbarbituricacid are dissolved in ml. of a 50:50 pyridinewater solution and 5 ml. ofacetic acid are added to convert the pyridine to the pyridinium acetatesalt. This solution is swabbed on a thin paper support and allowed todry. The element thus obtained is then imagewise exposed to a 2500 A.ultraviolet light source (Spectraline Model C-3F) at a distance of 6inches for 5 seconds. In the light struck areas a magenta image isformed whereas the areas not exposed to ultraviolet radiation remaincolorless.

EXAMPLE 2 Example 1 is repeated substituting 1,3-diethylbarbituric acidfor the 1,3-diphenylbarbituric acid. A magenta image is obtained in theexposed image areas.

EXAMPLE 3 Example 1 is repeated substituting 3-methyl-1-phenyl-2-pyrazolin-5-one for the 1,3-diphenylbarbituric acid. A purple to blueimage is formed in the exposed areas of the element.

EXAMPLE 4 Under saielight conditions photosensitive elements areprepared by imbibing into paper supports coated with a thin layer ofsilica gel, solutions prepared by dissolving 2 grams of the followingketomethylene compounds in 10 ml. of a 50:50 pyridine-water solution towhich 5 ml. of acetic acid has been added.

(a) 1,3-diethylbarbituric acid (b) 1,3-diethyl-2-thioba.rbituric acid(c) 3-cyano-4-phenyl-2(5H)-furanone These elements are then exposed bythe procedure described in Example 1. A magenta image is obtained in theexposed areas of the element employing 1,3-diethylbarbituric acid andblue images are obtained in the exposed areas of the other two elements.

EXAMPLE 5 Under safelight conditions photosensitive elements areprepared by imbibing into absorbent paper supports, a 1 molar solutionof Z-amino-l-methyl-pyrimidinium p-toluenesulfonate in methanol. Theelements are allowed to dry and they are then imbibed with 2 molarsolutions of the following ketomethylene compounds in methanol.

(a) 3-methyl-1-pheny1-2-pyrazolin-5-one (b)3-cyano-4-phenyl-2(5H)-furanone (c) 1,3-diethylbarbituric acid (d)3-ethy1-2-methylbenzothiazolium p-toluenesulfonate These elements arethen exposed for ten seconds to the exposure unit described in Example 1at a distance of 6 inches. In the exposed areas a red image is obtainedon the element containing B-methyl-1-phenyl-2-pyrazolin-5- one, a blueimage is obtained on the element containing3-cyano-4-phenyl-2(5H)-furanone, a yellow image is obtained on theelement containing 1,3-diethylbarbituric acid and a blue image isobtained on the element containing the 3-ethyl-2-methylbenzothiazoliump-toluenesulfonate,

while in the unexposed areas the elements remain colorless.

EXAMPLE 6 A coating composition is prepared by dissolving 1 gram ofB-methyl-l-phenyl-2-pyrazolin-5-one in 5 ml. of methanol and adding thissolution together with 1 gram of 2-amino-l-methylpyrimidiniump-toluenesulfonate to 5 grams of 20% gelatin at 40 C. To this coatingcomposition are added 15 ml. of water and 0.7 ml. of a surfactant (6.7%Triton X200, Rohm and Haas Co.) and it is coated at a thickness of 0.004inch on photographic paper. After drying at room temperature the elementis imagewise exposed to the light source described in Example 1. A redimage is formed in the exposed areas.

EXAMPLE 7 Example 6 is repeated substituting 2 grams of2,3-dimethylbenzothiazolium p-toluenesulfonate for the ketomethylenecompound. 'A blue image is obtained in the exposed areas of the element.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

What is claimed is:

1. A radiation sensitive element comprising a support and a radiationsensitive composition comprising as a first component a heterocyclicnitrogen compound selected from the group consisting of pyridinium saltsand pyrimidinium salts,

and a second component selected from the group consisting of a cyclicketomethylene dye precursor compound,

and a reactive cyclic ammonium quaternary salt which on exposure forms acolored dye.

2. A radiation sensitive element for preparing images by a dry processwhich comprises a support and a radiation sensitive compositioncomprising (a) as a first component a heterocyclic nitrogen compoundselected from the group consisting of pyrimidinium salts and pyridiniumsalts, and

(b) a second component selected from the group consisting of reactivecyclic ammonium quaternary salts and cyclic ketomethylene dye precursorcompounds selected from the group consisting of barbituric acids,2-pyrazolin-5-ones and 3-cyano-2(5H)-furanones.

3. An element as defined in claim 2, wherein the support is an absorbentsupport and the radiation sensitive composition is imbibed in thesupport.

4. An element as defined in claim 2, wherein the radiation sensitivecomposition is coated on the support in a film-forming binder.

5. An element as defined in claim 2, wherein the heterocyclic nitrogencompound is a pyrimidinium salt.

6. A radiation sensitive element for preparing images by a dry processcomprising a support and a radiation sensitive composition comprising(a) as a first component a heterocyclic nitrogen compound selected fromthe group consisting of (1) pyrimidinium salts having the structuralformula:

7 and (2) pyridinium salts having the structural formula:

wherein R and R are selected from the group consisting of hydrogenatoms, alkyl groups having 1 to 12 carbon atoms and aryl groups having 1or 2 rings, R is selected from the group consisting of hydrogen atoms,halogen atoms, alkyl groups having 1 to 12 carbon atoms, aryl groupshaving 1 or 2 rings and amino groups and X- is an anion, and (b) asecond component selected from the group consising of (1) a cyclicketomethylene dye precursor compound selected from the group consistingof (i) barbituric acids having the structural for- (iii) 3 cyano 2(5H)furanones having the structural formula:

o= c (IJH CN- :c-m

wherein Z is selected from the group consisting of oxygen atoms andsulfur atoms, R R and R are each selected from the group consisting ofalkyl groups having 1 to 12 carbon atoms and aryl groups having 1 or 2rings and R is selected from the group consisting of hydrogen atoms,alkyl groups having 1 to 12 carbon atoms and aryl groups having 1 or 2rings, and (2) a reactive cyclic ammonium quaternary salt having thestructural formula:

C-Rg

wherein R and R are each alkyl groups having 1 to 8 carbon atoms, and X-is an anion. 7. An element as defined in claim 6, wherein the firstcomponent is selected from the group consisting of pyridinium acetateand Z-amino-l-methyl-pyrimidinium p-toluene sulfonate, and the secondcomponent is selected from the group consisting of1,3-diphenylbarbituric acid,

1,3-diethylbarbituric acid, 1,3 diethyl 2 thiobarbituric acid, 3 methyl1 phenyl-Z-pyrazolin-S-one, 3-cyano-4- phenyl 2(5H) furanone, and3-ethyl-2-methylbenzothiazolium p-toluenesulfonate.

8. An element as defined in claim 6, wherein the first component ispyridinium acetate and the second component is1,3-diethyl-2-thiobarbituric acid.

9. An element as defined in claim 6, wherein the first component ispyridinium acetate and the second component is3-methyl-1-phenyl-2-pyrazolin-5-one.

10. An element as defined in claim 6 wherein the first component is2-amino-1-methyl-pyrimidinium p-toluenesulfonate and the secondcomponent is 3-cyano-4-phenyl- 2 (5 H) -furanone. I

11. An element as defined in claim 6 wherein the first component isZ-amino-l-methyl-pyrimidinium p-toluenesulfonate and the secondcomponent is 2,3-dimethylbenzothiazolium p-toluenesulfonate.

12. A dry photographic process for preparing images which comprisesimagewise exposing to actinic radiation an element comprising a supportbearing a layer of a radiation sensitive composition comprising (a) as afirst component a heterocyclic nitrogen compound selected from the groupconsisting of pyrimidinium salts and pyridinium salts, and

(b) a second component selected from the group consisting of reactivecyclic ammonium quaternary salts and cyclic ketomethylene dye precursorcompounds selected from the group consisting of barbituric acids,Z-pyrazolin-S-ones and 3-cyano-2(5H)-furanones to form a colored dyeimage in exposed areas of the element.

13. A process as defined in claim 12 which comprises imagewise exposingto a source of ultraviolet radiation an element comprising a support anda photosensitive composition comprising a first component selected fromthe group consisting of pyridinium acetate andZ-aminol-methyl-pyrimidinium p-toluenesulfonate, and a second componentselected from the group consisting of 1,3-diphenylbarbituric acid,1,3-diethylbarbituric acid, 1,3-diethyl-Z-thiobarbituric acid,3-methyl-l-phenyl-Z-pyrazolin-5-one, 3-cyano-4-phenyl-2(5H)-furanone and3-ethy1- Z-methylbenzothiazolium p-toluenesulfonate.

14. A process as defined in claim 13 wherein the first component ispyridinium acetate and the second component is1,3-diethyl-2-thiobarbituric acid.

15. A process as defined in claim 13 wherein the first component ispyridinium acetate and the second component is3-cyano-4-phenyl-2(5H)-furanone.

16. A process as defined in claim 13 wherein the first component ispyridinium acetate and the second component is2,3-dimethylbenzothiazolium p-toluenesulfonate.

References Cited UNITED STATES PATENTS 2,999,035 9/1961 Sahler 117-3683,395,018 7/1968 Read 9690 2,967,785 1/1961 Allen et al. a- 11736.82,984,664 5/1961 Fry et al 96-106 3,219,470 11/1965 Lassig 117-1553,396,017 8/1968 Bacon et al 96-27 WILLIAM D. MARTIN, Primary ExaminerM. SOFOEL-EOUS, Assistant Examiner US. Cl. X.R.

